Monday, July 18, 2016

The WiFiChron code, with support for ESP8266, nearly reached the program memory limit of ATmega328, yet still missing a few features, the most important being the much needed debugging capability.

Naturally, the next step in WiFiChron's evolution was to upgrade to Atmega644P/1284P. Since there was no room on the board for the 40-pin DIP package, I settled for the SMD version.

The schematic is shown below.

Although functional, the board I designed is far from perfect:

requires pull-up resistors for buttons; I relied on software pull-up, but that does not work in the current Sanguino library;

requires a couple of more decoupling capacitors;

(I soldered all these extra parts on the bottom side of the PCB, as shown in the next photo. The 595 shift-register is soldered on the bottom by design. The next revision will have the currently missing parts in the SMD package.)
The WiFiChron-1284 board has the same dimensions as the previous revision, and it still fits in the Serpac A20 box.

I burned the bootloader using the on-board ICSP header.

Thanks again to MikeM, who contributed the software (Arduino 1.6.7 - compatible), featuring: